Section: Niner Insider Blog

Richardson will join a backfield that includes Donald Brown and Ahmad Bradshaw, who rushed for 116 yards on 27 carries against the 49ers last year as a member of the Giants. Vick Ballard, who led the Colts in rushing with 814 yards last year, sustained a season-ending ACL tear in practice last week. …

The 49ers’ running backs – Gore, Kendall Hunter and Anthony Dixon – have 81 yards on 38 carries (2.1 yards per attempt). Gore has 60 yards on 30 carries, his lowest two-game total in contests he has finished (i.e. not left early because of an injury) since his rookie season in 2005. …

“I wish I’d paid more attention to those conversations now, I guess,” Luck said. “Coach Fangio was a great coach when I was at Stanford. Guys really loved him. He did so much for our defense there. I think as a quarterback – his door was always open for anyone to come talk to him. …

Marecic, 24, who played for Harbaugh at Stanford, was released by the Browns on Aug. 27 and had a tryout with the 49ers a few days later. Marecic was among Cleveland’s first wave of roster cuts after a forgettable 2012 season. …

Niners staring nose tackle Ian Williams will undergo surgery today for a broken ankle he sustained in Sunday’s 29-3 loss to the Seahawks and will be placed on the season-ending injured-reserve list, Jim Harbaugh said today. …